Fifty-one years ago, The Feminine Mystique ushered in the movement that promised to liberate parents from the cultural straitjacket of rigid gender roles. We asked fathers to be more than material providers to their children. Stop pacing the maternity ward waiting room and join your wife in the delivery room. Help pay for diapers, formula, and children’s books, yes. But don’t expect Mom to change all the diapers, do all the feeding, and read all the bedtime stories.

Dads got the message. The most recent study of dual-earner families reported that on a typical workday, fathers spent a little more than 1.5 hours directly engaged with their three-month-old infants. This may not sound like a lot, but it amounts to 41 percent of the total time that the two parents interacted with their infants. Not quite half. But getting there. And babies are benefitting from all this time with dads.

Whether observed in the laboratory or in natural settings, dads demonstrate over and over that their presence matters a great deal to their children from the baby’s birth onward. The more time parents spend with their infants and toddlers, the better able they are to read their baby’s signals and respond sensitively to their children’s needs. It takes nothing away from mother-child relationships when dads change diapers and bathe babies. For some important areas of development, such as vocabulary and children’s persistence in the face of obstacles and frustration—the “can-do” attitudes that are essential to success in life—fathers may have a greater impact than do mothers.

When it comes to encouraging hands-on shared parenting, society imposes a curious double standard.

All this is good news for children in two-parent homes. But not such good news for children whose parents separate. When it comes to encouraging hands-on shared parenting, society imposes a curious double standard. When they live with their children’s mother, we expect dads to assume their fair share of parenting responsibility. When parents separate, though, some people think that young children need to spend every night in one home, usually with mom, even when this means losing the care their father has been giving them.

In her recent Family Studies blog post, Professor Linda Nielsen showed how this idea arose from seriously flawed interpretations of data that were repeated often enough to acquire the aura of truth. Just last month a popular United Kingdom authority on parenting relied on such interpretations to conclude: “Findings strongly suggest that shared care that includes spending nights, or even a single night at a time, away from ‘home’ and mother is seldom in the best interests of children under around four years of age irrespective of the families’ socio-economic background, their parenting or the co-operation between the parents.” Many of us still think that it is Mom’s exclusive role to care for infants and toddlers, and that we jeopardize young children’s well-being if we trust fathers to do the job.

Where does science stand on these issues? To find out, I spent two years reviewing the relevant scientific literature and vetting my analyses with an international group of experts in the fields of early child development and divorce. The American Psychological Association published the resulting consensus report with the endorsement of 110 of the world’s leading researchers and practitioners. One of the signatories was UVA’s Emerita Professor of Psychology E. Mavis Hetherington.

Shared parenting should be the norm for children of all ages whose parents live apart from each other.

We reached two main conclusions. First, the social science evidence on how healthy parent-child relationships normally develop, and the long-term benefits of those relationships, supports the view that shared parenting should be the norm for children of all ages, including very young children, whose parents live apart from each other. Second, restricting fathering time to daytime hours until children enter kindergarten is not the best arrangement for most children if we want to give them the best chance for normal relationships with their fathers. Naturally, shared parenting is not for all families. In general, though, we favor having young children spending some nights at their fathers’ homes, and find no reason to postpone overnights until children turn four.

It is time to resolve our ambivalence and contradictory ideas about fathers’ and mothers’ roles in their children’s lives. If we value Dad reading Goodnight Moon to his toddler and soothing his fretful baby at 3 a.m. while the parents are living together, why withdraw our support and deprive the child of these expressions of fatherly love just because the parents no longer live together, or just because the sun has gone down?

Richard A. Warshak is a clinical professor of psychiatry at the University of Texas Southwestern Medical Center. He is the author of “Social Science and Parenting Plans for Young Children: A Consensus Report,” published in Psychology, Public Policy, and Law, Divorce Poison: How To Protect Your Family From Bad-mouthing and Brainwashing, and Welcome Back, Pluto: Understanding, Preventing, and Overcoming Parental Alienation.